With the progressive development of display technology, a trend of integrating a touch panel function into a liquid crystal display panel is becoming more and more popular.
At present, the development routines for the embedded touch display screen mainly involve two kinds of technology: on-cell touch and in-cell touch. The difference between these two kinds of technology is as follows. The on-cell touch is a touch technology realizing the touch panel function between the color filter substrate and the polarizing plate. Specifically, a touch sensing component layer in the touch panel is fabricated on a base substrate of the color filter substrate and attached to the color filter sheet. The in-cell touch is a touch technology realizing the touch panel function within pixels. Specifically, the touch panel function is integrated into the color filter substrate and thus embedded into liquid crystal pixels. Compared with an on-cell touch panel, the in-cell touch panel has advantages such as thin thickness and light weight, which reduce the thickness of the panel and can decrease manufacturing cost as well.
In order to accord a touch display screen with a lighter and thinner display panel, embedded touch display screens in which touch electrodes are fabricated inside liquid crystal display panels have appeared; and the touch electrodes include touch scan lines and touch sensing lines. For example, touch scan lines and touch sensing lines are directly added on a thin film transistor (TFT) array substrate to implement touch function. There are formed two layers of strip-like transparent indium tin oxide (ITO) electrodes that cross each other in different planes and not electrically connected on the surface of the TFT array substrate, function as touch scan lines and touch sensing lines of the touch display screen respectively, and form inductive capacitors at the intersections of the two layers of ITO electrodes in different planes.
The operation mechanism of the capacitive embedded touch display screen is as follows. While touch scanning signals are applied to the touch scan lines, voltage signals coupled out by touch sensing lines through inductive capacity are detected. In this process, if a human body contacts the touch display screen, the electric field of human body at the touched position will act on the respective inductive capacitors to change the capacitance value thereof, and in turn change the voltage signals coupled out by touch sensing lines, and contact position can be determined according to the change of voltage signals.
With the improvement of product resolution, requirements on touch accuracy are becoming higher and higher. In order to obtain high touch accuracy, it is required to reduce the line widths of touch scan lines and touch sensing lines. However this would result in increased resistance of the touch scan lines and the touch sensing lines, and hence resulting in delay of signals.